The invention relates generally to the field of semiconductor technology and in particular to a layered high frequency capacitor suitable for RF applications.
The increasing need for communications has been a consistent driver for expanding the spectrum utilized for wireless communications. In recent years frequencies in excess of 10 GHz have become commonplace in satellite video and data transmission, while frequencies up to 3 GHz are common in cellular communications. In general, components designed for such high frequencies are also known as radio frequency (RF) components. The generation and detection of RF requires precision passive electronic components, such as capacitors, inductors and resonant filters. Unfortunately, precision passive electronic components are typically expensive and as such prevent the rapid spread of technology based on these frequencies.
Semiconductor manufacturing technology is well developed, and is an excellent technology for reducing the cost of devices and components, while maintaining a high level of precision and repeatability. Many prior art techniques exist for manufacturing capacitors, unfortunately the need for high precision as required for RF applications, and low cost has not been met. In particular a number of barriers to precision control include diffusion of any deposited metal, lack of adhesion of a deposited metal to a dielectric and precision control of the height of a dielectric.
U.S. Pat. No. 6,498,364 issued to Downey et al. describe a capacitor for use in a semiconductor device having a damascene interconnect structure, such as a dual damascene interconnect, formed over a substrate of a semiconductor wafer. The use of a damascene structure adds complexity in the processing due to the polishing required. This increases the end cost of the devices.
U.S. Pat. Nos. 6,538,300 and 6,621,142 issued to Goldberger et al. is addressed to a precision high frequency capacitor including a dielectric layer formed on the front side surface of a semiconductor substrate and a first electrode on top of the dielectric layer. The semiconductor substrate is heavily doped to provide for an electronic discharge protection diode. The use of a heavily doped substrate increases the RF losses in the capacitor and inhibits the integration of inductors or filters.
Thus, there is a need for a precision RF passive component, such as a capacitor, which is preferably suitable for low cost production and integration with other RF components on a single common substrate.